Factor VIII

Factor VIIIc or factor anti Hémophilique has is a Glycoprotéine present in plasma at the state of traces, playing a part of cofactor in the cascade of the Coagulation.

Structure and production

Synthesis

Gene of factor VIII

The genes (gene of factor VIII and gene of factor IX) which orchestrate the manufacture of the factors of coagulation are located on X chromosome. The woman has two X chromosomes, one says that it is XX. If the gene located at the level of one of X chromosomes is carrying an anomaly, the gene located on the other X chromosome, which in the vast majority of the cases is normal, will at least partly provide the function reserved initially for two genes: the woman will thus not present or few clinical signs. However, this woman will be " conductrice" hemophilia and will be able to transmit it to its descent. Because of the potential absence of clinical signs, several generations of conducting women can follow one another without the knowledge. Conversely, at the man who has an X chromosome and one Y chromosome (it is XY), any anomaly of X chromosome will generate a hemophilia. When an hemophiliac has children, his/her daughters will be systematically conducting, having " hérité" X chromosome carrier of the anomaly of their father. The type and the degree of the hemophilia remain identical within a family.

Pathologies associated with deficiency in factor VIII

The biological examination (blood test to proportion factor VIII/IX) at the same time makes it possible to define the type (has or B) and the form of the hemophilia (severe, light or moderate). The severe forms are generally diagnosed as of the birth in front of a hématome which has occurred spontaneously or after a tiny traumatism. The moderate forms they less frequent and are generally caused by an even light traumatism In the light forms, the hemorrhages occur only following one serious wound or with an operational act. even a minor surgical operation (dental extraction) can be at the origin of hemorrhagic accidents.

External hemorrhage

the external hemorrhage is visible since blood runs out by a wound located on the surface of the body. The person can bleed of the nose at the time of a cold or after an exposure prolonged to the sun. It can also bleed of the mouth (too intense brushing of the teeth, bite of the mucous membrane of the cheeks at the time of the chewing…).

Hématome

The hématomes can occur at any place of the body. It is consecutive with a traumatism being accompanied by appearance of pains and a perceptible swelling to palpation, at the place of the Traumatisme. Its principal characteristic occurred of a coloring first of all blue violet which is transformed gradually into greenish yellow coloring which disappears at the end of approximately 15 days.

When it is intramuscular, it can cause a temporary loss of the normally assured function by the muscle. The most frequent hématomes are subcutaneous (under the skin) and without gravity. Certain intramuscular localizations are particularly dangerous and justify an immediate consultation and the installation of a substitute treatment: neck, throat, language, abdomen, muscle psoas on the level of the basin, genitals… the intracerebral hématomes although rare constitute the leading cause of mortality. They will have to thus be suspectés in front of any sign evoking a cerebral attack: eye trouble, headaches, giddiness, faintness, loss of consciousness… a substitute treatment will then immediately be founded.

Hémarthrose

Blood runs out inside an articulation (knee, ankle, elbow, finger) and finishes, in the absence of substitute treatment, by the " bloquer". This hemorrhage can be caused by a Traumatisme (blow, falls) or make following a prolonged effort (long walk, practical of a sport, port of an important load). It can also be spontaneous. At the beginning, the patient locally feels tinglings and a feeling of heat, then the articulation " enfle" , reddens and becomes painful. To avoid the pain, the person often adopts an antalgic position (with the folded member). These attacks are serious because not only they undermine the social life and professional of the patient but also because, repeated and in the absence of substitute treatment, they involve the appearance of a chronic Arthropathie evolving unrelentingly to the destruction of the articulation

Factor VIII as a medication

Treatments

The basic salary which makes it possible to stop or to prevent the bleedings at the people reached of Hémophilie has is the treatment by factor of replacement. It is about a perfusion (injection in blood circulation) of concentrate of factor VIII managed to prevent or control the hemorrhage. These concentrates come from two sources:

of the human Plasma (a component of blood) or

of a cellular line obtained by genetic engineering (artificial) by the means of the technology of recombination of DNA.

In both cases, the protein of factor VIII is almost identical to that which is lacking in the blood of the hemophiliacs. After a perfusion of concentrate, all the proteins necessary for coagulation are in place. The blood of the hemophiliac becomes " normal " , at least during a few hours. That makes it possible the Caillot to be formed where the blood-vessel is damaged

Complications of the treatments

Inhibiters

It happens that the organization reacts against the factor injected by manufacturing Anticorps. One speaks then about occurred about a Inhibiteur. A biological examination makes it possible to proportion its rate.

Transmission of infectious agents

Three viruses indeed had dramatic consequences in the hemophiliacs: the virus of the human immunodéficience (HIV), the virus of hepatitis B and the virus of hepatitis C. the contaminations by these three viruses are not observed any more because of the effectiveness of the processes of viral inactivation used currently during the manufacture of the concentrates of factor VIII of coagulation. Lastly, the risk of contamination by new infectious agents as request them hypothetical remainder in the actual position of knowledge

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